Of the Box

Evolution Could Destroy Our Ability To Tolerate Alcohol

Recent studies have shown that we are still evolving and now, new research published in Nature Ecology and Evolution suggests we could be developing a gene that wrecks our tolerance for alcohol.

Researchers at the University of Pennsylvania analyzed the genomes of some 2,500 people from 26 populations across four continents using data collected by the 1,000 Genomes Project. The team then singled out specific traits or “genomic hotspots” that pop up in various, divergent populations – say, changes to an area of the gene responsible for producing glycophorins, which has occurred in parts of Africa and Asia. For this to have happened, the mutation must have emerged independently in these two different populations and persisted. Alternatively, if there had been just one initial mutation, it would have had to travel like Speedy Gonzales across the two continents.

“What this new study shows is that selection has also been tending to make some genes similar between populations,” John Hawks, from the University of Wisconsin-Madison, told New Scientist, “to help people adapt to recent changes in our ecologies”.

In the study, the researchers highlight five areas of recent change. This includes the adaption to the glycophorin gene cluster – which has been linked to malaria resistance – in Asia and Africa, two areas where the mosquito-borne disease poses a severe health risk. In Europe, the team noticed an increase in genes related to the breakdown of an amino acid called homocysteine, which in high levels can cause heart disease. Meanwhile, all five African populations studied showed changes to a gene that affects the positioning of the urethral opening (DGKK) and, in non-African populations, there appeared to be positive selection for two genomes inherited from our Neanderthal neighbors.

Most interestingly, perhaps, are the modifications to the alcohol dehydrogenase cluster (ADH), which could be changing how we process alcohol. Dehydrogenase is the enzyme that breaks down alcohol, which it does by metabolizing it into a compound called acetaldehyde. This toxic chemical is responsible for your pounding headache the morning after a night out. Fortunately, the body is able to turn this into another substance that is non-toxic called acetate relatively quickly and we feel better after a day or so.

However, evolution could be finding a way to curb humanity’s alcohol addiction by creating new variants of ADH that affect our tolerance to booze and our body’s ability to convert acetaldehyde to acetate. Essentially, it means we would feel ill after just a small amount of drink.

So far, these genes have only been detected in East Asia and West Africa, but time will tell how far they spread.

For more predictions on how humans will look and behave in the future, check out this video from AsapSCIENCE.